RADON MEASUREMENTS IN INDOOR WORKPLACES

Radon measurements in several office buildings located in Tokyo were c arried out with two types of device to study the time-dependent radon concentration in indoor workplaces. Both types of device use the elect rostatic field for the collection of Po-218 onto the electrode of the detector. One provides an average radon concentration throughout the d ay. The other, in which a weekly timer is installed in the circuit of the electrode of the device, provides an average radon concentration d uring working hours (9:00-17:00, Monday-Friday). Although radon concen trations in Japanese dwellings have been found to be generally low, re latively high concentrations were observed in the office buildings. No consistent seasonal variation was recognised in this study. Little di fference of average radon concentrations between working hours and the whole day was found throughout the year in two offices. On the other hand, a significant difference was observed in other offices. The oper ation of an air conditioner might change the radon concentration durin g working hours. From the results of radon measurements the average ef fective dose in the workplace was estimated to be 0.23 mSv for 2000 wo rking hours in a year.